In the usual methods for bending and tempering glass, as used, for example, in manufacturing curved motor vehicle glass, the glass to be bent is heated up to the bending temperature in the horizontal position inside a continuous furnace, is bent in a bending station and is heat tempered in a tempering station which follows, by rapid cooling in air. In all the known methods of this type bending frames which correspond in respect of their geometric configuration to the desired shape of the glass to be manufactured are used for the bending and/or for transporting the bent glass and/or for tempering. For example, such bending frames are used in the method known by the name of gravity bending as described in document DE 2 945 776 C2. In the case of this method, the flat glass to be bent is lifted up by a suction head, is deposited on such a bending frame and is conveyed therewith into the tempering station. In the case of the method known as compression bending, such bending frames are used as peripheral bending forms with which the glass is pressed against a convex upper bending form which covers the entire surface. In a conventional embodiment of the compression bending method, the bent glass is passed through a tempering station situated downstream with the aid of this bending frame used as a bending form. In another known embodiment of the compression bending method the glass pressed with such a bending frame is held by suction against the upper bending form and after the bending frame has been removed it is deposited on another frame with which it is then transported to the tempering station. There are also known methods for bending and tempering glass in which such bending frames are used only for transporting bent glass, while the bending force in the bending station is applied using other means, for example a flow of hot air flowing upwards or using press tools which cover the entire surface.
Insofar as such bending frames are used as frames for carrying the glass into the tempering station, they are provided, on their upper side, with projections or with recesses so that the blown air directed against the lower face of the glass can reach the region around the edge of the glass and thus cool this point rapidly enough to obtain the required tempering.
It has become evident that the known methods, in which the glass in its softened bendable state is bent with known bending frames and/or is carried by these, do not always lead to optimum results. In particular, when bending and/or tempering glass with an opening formed inside its face, it may happen that the bent glass exhibits in its bent profile discontinuities which have a disturbing optical effect. The presence of one or more openings inside the glass, which also in some circumstances have larger dimensions, may, however, be desired, for example when transmitters or receivers of signals have to be arranged inside the glass for electromagnetic radiation which is excessively attenuated if it has to pass through the glass. The discontinuities in the bent profile occurring in the case of glass provided with openings may arise both during the bending operation proper and after the bending operation proper, under the effect of gravity on the glass, while the glass is resting in the deformable state on the bending frame.